Telephone system.



A, D. T. LIBBY. i TELEPHONE SYSTEM.

APPLICATION FILED JULY 15,1909.

A. D. T. LIBBY.

TELEPHNE SYSTEM.

APPLICATION FILED JULY15, 1909.

1,008,476, Patented sept. 19,1911.l

2 SHEETS-SHEET 2.

F/ e. i?,

TW 55555 v @VW LEU UNITED srarns PATEN- FFIGE.

ALBION D. T. LIB 'BY, OF EL'YR-IA, OHIO, ASSIGNOR TO THE DEAN ELECTRIC COMPANY,

OF ELYBIA, OHIO, .A CORPORATION OF OHIO.

TELEPHONE SYSTEM.

tocante.

Specicaton of Letters Patent. Patented Sept. 19, 1911,

Application filed July l5, 1.909. Serial No. 507,820.

To all whom it may concern.'

Be it known that I, ALBION D. T. LIBBY, a citizen of the United States, residing at Elyria, in the county ofvLorain and State of Ohio, have invented certain new and useful Improvements in Telephone Systems;

l and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the artlto which it appertains to make and use the same.

-This invention relates to telephone systems, and I have in mind more particularly the class of telephone .systems commonly known as house or intercommunicating system. The use of such systems which are installed inside of buildings and which permit the intercon'ununication between the substations on the system, is well known in the telephone art. My purpose is to produce a convenient and satisfactory arrangement to connect any of the substations of such an intercommunicating system to subscribers on outside lines. I show a trunk circuit connected at its other end with an exchange adapted to connect the intercommunicating system with outside lines. To effect this, I utilize one of the interconnecting stations as an attendant station which is adaptedl more particularly to answer calls coming in over the trunk and to transfer them to the desired station. The central station is provided with a signal which is operated when the subscriberscircuit is interruptechto indica-te the termination of the use of a. line; On observing this signal, the operator takes down the connection. Unless special means are provided, this signal will be operated and the connectioninterrupted when the attendant in the intercommunicating system is transferring thecall. I provide means to prevent this and I place such means under the control of the called station. I also provide means whereby the atttendant may release this`circuit independent-ly of the called station, and which may be utilized when the called station fails to respond. In systems of this kind, when the called subscriber does not respond, the attendant, not having been informed of this fact, leaves the trunk cir-v cuit tied up, as the holding means which prevents the display of the disconnect signal, will remain operative. To avoid this, I provide means which will indicate to the attendant station that t'hecalled subscriber has not answered the call.

More minutely describing my invent-ion, but not limiting myself thereto, I provide a holding circuit across the trunk line which is closed when the attendant answers, and a. locking circuit therefor, closed when the call is transferred. An electromagnet which is included in circuit with the attendants instrument when she plugs i-n on the trunk line, pulls up its armature, closing the holding circuit. A locking relay in the holding circuit fails to operate, owing to the fact that it is shunted by the attendants set. lVhenthe attendant disconnects her set from the tiiink by the release of the trunk key, the relay in circuit therewith being slow acting, holds up its armature long enough for the locking relay to be operated to hold the trunk. This locking relay also closes a circuit through a special signaling arrange-- ment which immediately actuates. This signal continues until the called station comes in on the trunk. A condenser is placed in one side of the trunkand is shu-nted by a relay which controls the holding circuit. Then the called stationcomes in,Y on the trunk, this relayis energized to interrupt the holding circuit and denergize the locking relay' so that the special signaling means is rendered inoperative.

In this preliminary description I have endeavored to elucidate some of the features and objects of my invention, and I do not intend to be limited thereby.

M v invention will be best understood by reference-to the following description when taken in connection with the accompanying illustrations showing one specic embodi ment thereof, while its scope will be more particularly pointed out in the appended claims.

Figui-e 1 is a diagram of the circuit ai rangement of my improved system. Fig. 2 is a side elevation of a' set of keys such as I may use at each station. Fig. 3 is an end elevation of Fig. 2 showing the ringing contact.-

Referring to the drawings and to the embodiment. of my invention there shown, I have illustrated in the diagram of Fig. l an attendants station at A andother stations on the intercommunicating system at C and D.

' including the n m-iiuluctr-ie `connected lto the 'intercoinniunieating lines through retardation eoils.

Each ofthe stations is associated with the trunk andeaeh of the 'intereonnnunicating lines, and` is adaptedto be connected thereto by `push 'button switches shown alt the attend'ants station at H, 4K1, K2, and T.

T represents the trunk bntton,`.K1`that appertaining to the first station C, and rK2 that appertaining to the second station D.

H is Ithe homer button.

.211 and 12'are the springs 'for theV ringing circuits, and 'areeontrolled by the push buttons'as shown'in Figs. 2 and These buttons are so varranged that `the contacts of the' ringing circuit are closed only'when the buttons are in the way-down or tinal position.= The arrangement is such that 'on dei pression o'lfone button, previously depressed buttons'are releasedl' This arrangement is old and well known in tbeart,and is eollateral and auxiliary to my invention. A signal S is bridged across the `trunk line. Signals S1, S2 and S are provided at the various lstations for interconinninicating signaling. I provide a condenser l?, in one .side of the trunk line. A relay R1 is eonl .neeted inl multiple with' the condenser. A relay R2 having a non-inductive resistance 14: in multiple therewith, is connected. in circuit with the attendants substation set in such a way thatit is energized when her set is connected with the trunk line. Vhen they circuit through the :q :lay llg is broken, the back eleetreinotivc 'force sends an i1npulse o'l current through the parallel branch, resistance l-t. This current, eausesthe relay to hold up tor a short interval of time after the interruption ot the circuit. t2 controls the switch iti-16 which is placed .in the holding cireuit, A relay il in the holding circuit' is adapted to eontrol the two switches Q-jt--95, QGf-Ql At 21 l provide a hey to control the holding circuiti. it QS provide a buzzer whose circuit is controlled by the relay lR at the switch @GN-27. The substation sets at the int'ereonnnunieat-i'ng stations include the usual transmitters, receivers, andgravity operated switch hooks. At the attendants station this hook is shown at L, having the lower contacts 31 and 32 and the upper contacts Qt) mall-20. .'\.t station C the hook is shown at /z/ haring lower contacts 555-36 and upper contacts 33H34.

ln describing the operation of lny system, 1 will assume that a call comes in over the trunk line. is answered by the attendant, and is transterrtal to` station C. 0n observing i the operation of the signal S, the attendant substation set including the receiver rthe transmitter tthe vrelay R2-Llll243- 17, to the other side of the trunk 2. Relay R2 isenergized attracting the yarmature 1G andielosing a bridge across the. trunk line as 4follows: troni the side '1., through ettm 23-22-4,5 the switeh 2l-20--lt3-15 l9-- relay h"` -lSs--liM to the other side l et the trunk. The ycurrent over'the trunk line may be strong enough tzoenergize the relay R3 in which ease it will .innnediately pull up to lock itself. As a rule, however, the resistance of this relay is sutlicient. to pre-rent its operation aslong as it is shunted by the substation bridge. 'the atteiulant is intornied by the central operator that station C is desired. The attendant pushes in the button K1 tagrrcspoiuling to station C. 'l`hisreleases the trunk button 'if sol that the attendantis set is disconnected troni the trunk line. The relay .t2 being sloiv acting, as described, holds up its armature tor a short tinie after the circuit is broken, dur- `ing which the relayR3 now being energized by the tnll current oi the trunk line, attracts its armature 25 and 27, locking itselt and retaining the bridge through the following eircui .troni the Iside l ot the trunk line- 't Ath-Q3 2--'t5-Ql--2O ifi--l--ltiL-l S-- 17A-- to the other side 2. To ring station C the attendant pushes the butto-n IU to its way-down position, closing the contactaI ]l--5(). ',l`he 'following circuit is then coinpleted: troni. the positive side ot battery B t) l--;l (i-.w/z -3 fvwti'll lb-'1 L2-- 5ffl'-55- 5-ti(i--57'5S v- 59*lfi^-50A-l l- (lt-ltrto the negative side ot battery l. ',lhis operatesthe signal S at the station C. During this time the disconnect signal at the central station is prevented troni operating by the bridge across the trunk line through the relay R3, previously described.

tlhould the station C not answer innnediand ring the desired station 'troni time to tinie until answered, l)nring this interval a circuit will be closed through the buv/er QS as follows: iroin the positive `side ot battery T S) (S1t--- 32 71,- 3 1-62--96-27 -28- t3-t0- and 10 to the negative side ot the battery. lVhen the station (l does answer he is informed that he is wanted on the trunk line. lle imniediately depresses the trunk button T1. `Sheuld he il'ait to do so, the. attendant is apprised ot that tact by the operation ot the buzzer through the circuit previously described. The minnnnnieation between stations A and (l takes place as l'ollows: 'In answering the signal S, the party C depresses the home button lll, placingl the substation set in bridge ot the linesI and t3.

Conversation takes place over the following circuit: t at station A.-70-71-72-73-6- 74-75-76-7 251- the substation set at C including the receiver 111-34,- and the receiver having been removed from the hook, the hook L133787980-81 55 5 56 -57-58-5940-29-i30- back to t'. The battery Br is vbridged across the lines 5 and 6 and supplies energy for this circuit. Should the party C fail to come in upon the trunk, the attendant may release the holding bridge by operating the switch 21 which would interrupt it. Assuming that station C depresses the button T1, the following circuit will be closed: l- 90-91-92-93-784-33-L1-3tthe sub station set- 94L--95-96--97-toI the other side of the trunk 2. The relay R1 will be energized over this` circuit to attract its armature 23 and interrupt the holdin bridge at 22-23. The circuit of R3 will be broken and its armatures released interrupting the locking circuit and the circuit of the buzzer. The station C is now in communication with the party on the trunk line, the voice currents passing through the condenser 13 which is in multiple With R1. When the conversation is terminated, the party at C restores the receiver to the hook, interrupting the continuity of the circuit, and operating the disconnect signal at the central station, whereupon the operator pulls down the connectionsrestoring the system to normal condition. v

`While I have shown this particular. form of slow acting relay, it is obvious that Imay employ any other form which performs the required function. Itl will also be obvious to those skilled in the ait, that numerous and extensive departures 'from the form and the details of the apparatus here shown,

.may be made without departing from the spirit of this invention, the same being herein shown solely for the purpose of clearly illustrating one specidc embodiment thereof. y

I claim:

l. In an intercommunicating telephone system, a plurality of stations and conductors interconnecting them, one et said stations constituting an attendants station, a main exchange trunk line extending to such stations, holding means at the attendants station for holding a main exchange connection through such trunk line while calling the -desiredinterconnected station, a normally 4closed switch in said holding means, and means controlled only from the called station for opening said switch and releasing the holding means.

2. In an intercominunicating telephone system, a plurality of stations and conductors interconnecting them, one of said stations constituting an attendants station, a main exchange trunk line extending'to such stations, holding means at the attendants station for holding a main exchange connection through suoli trunk line while calling the desired interconnected station, a normally closed switch in said holding means and means operated only by the removal of the receiver at the called station for opening said switch and releasing the holding means.

3. In au intercommunicating telephone system, a plurality ofi stations and conductors interconnecting them, one ot' said stations constituting an attendants station, a main exchange trunk line extending to such stations, holding means at the attendants station for holding a main exchange connection through suoli trunk line while calling the desired interconnected station, a norma-lly closed switch in said holding means,

vand means operated only by the closure ot' a talking circuit through the trunk line at the called station for opening said switch and releasing the holding means.

4. In an inter-communicating telephone system, a plurality of stations and condite-- y means controlled from the called station for.

opening said switch and releasing the holding means, and a manually operable switch in said holding means adapted to release the holding means independently ot said liist named releasing means.

5. In an intercommunicating telephone system, a plurality ot stations and conductors interconnecting them, one of said stations constituting an attendants station, a main exchange trunk line extending to such stations, holding means at the attendants "station for holding a main exchange connection through such trunk line while calling the desired interconnected station, and

a slow acting relay in the attendants trunking circuit controlling said holding means. 6. In an intel-communieating telephone system, a plurality ot stations and conduetors interconnecting them, one ot said stations constituting an attendants station, a main exchange trunk line extendingto such stations, holding means at the attendants 'station for holding a main exchange con` nection through such trunk line while callingthe desired interconnected station, and a slow acting relay operated when the attendant comesA in on the trunk to control said holding means.

7. In an inter-communicating telephone system, a plurality of stations and concluetors interconnecting them, one of said stations constituting an attendants station, a main exchange trunk line, extending to such stations,` holding .means .a .f the attendants l station for holding a main exchange connection through such trunk line While calling the desired interconnected station, a slow acting relay in circuit with the attendants set, and locking means -for said holding meansv in multiple with the attendants set and the slow acting relay.

8. .In an intercommunicating telephone system, a plurality of stations and conductors interconnecting them, one ot said staholding means adapted to operate while the control of the slow acting means prevail.

9. In an intercommunicating telephone system, .a plurality ot stations and conductors interwnnecting them, one of such stations constituting an attendants station, a

main exchange trunk line extending to such stations, means for calling a desired station from. the attendants station, a signal at the attendants station brought into operative condition by suoli act ot calling, and means controlled by v'the called station for retiring .such signal to its inoperative condition.

10. In y'an inter-communieating telephone system, a plurality o stations and conductors interconnectingthem, one of such sta tions constituting an attendants station, a. main exchange trunk line extending to such stations, holding means at the attendant-s station `for holding a main exchange connection through such trunk line while calling ,the desired interconnected station, means Jfor calling a desired station trom-the attendants station, an indicator circuit at the attendants station closed by such act. of calling, means controlled trom the called station tor interrupting such indicator circuit and for rcleasing such holding means.

ll. vIn an intercomniunicating telephone syst-ein, a plurality ot stations and conductors interconnecting them,` one ot such staltions constituting van attendants station, a.

main exchange trunk line extending to such stations'holdmg means at the attendants station tor-holding a main exchange connection lthrough*suchtrunk line While calling the desired interconnected station, means for calling a desired station from the attendants station, an indicator circuit at the attendant-s Localicev station closed by such act of calling and means operated by the reino val ot the rcceii'er at the called station for interrupting such indicator circuit and for releasing such holding means.

l2. In an interconiiniinicating telephone system, a plurality ot stations and conductors interconnecting theni, one of such sta,- tions constituting an attendant@ station, a main exchange trunk line extending to such stations, holding means at the attendants station for holding a main exchange eonnecn tion through such trunk line irhile calling the desired interconnected station, ni ians 'tor calling a desired station from the attendants station, an indicator circuit at the at tendant 's station closed by such act ot calling. and means operated by the removal ot the re ceiver at. the called station tor interrupting` such indicator circuitand tor releasing such holding means.

13. In an intercommunicating` telephone system, a plurality of stations and conductors interconnecting them', one ot such sta tions constituting an attendants station. a, main exchange trunk line extending to such stations, a relay connected to such trunk line, an electrical path ot low r closed through contacts on such relay by the' act ot calling a desired station, and means for controlling the operation ot such relay trom the called station.

lil. In an ii'iterconiinunicatingT telephmiel Asystem, a plurality ot stations and conductors interconnecting them, one of such stations constituting an attendants station. a main exchange trunk line extending to such. stations, a relay connected to such trunlt line, an electrical path ot loiy resistance closed through break contacts on such rela y by the act ot calling a desired station, and means for energizing such relay from the called station by establishing thcreat a talleingconnection with the trunk line.

l5. In an intcrcommunicating telephone system, a plurality of stations and conduc tors interconnecting them, one ot such stations constituting an attendants station, a main exchange trunk line extending to sui-li stations, keys at the attendants station tor calling a desired one of .theinterconnected stations, a buzzer at the attcndants station, means for closing the buzzer circuit when one of such keys is operated. and means operated by the establishing at the calledv station ot a talking circuit with the trunk line tor interrupting such buzzer circuit.

1(5.In an intercominunicating telephone system, a plurality ot' stations and conductors interconnecting them, one ot such stations constituting an attendants station, a main exchange trunk line extending to such stations, keys at the attendants station tor calling a desired one ot the interconnected stations, a firstI relay controlled in its ope a- .2 Vance l Ot.

tion by the act of calling, such relay by its operation serving to close signaling eir- Quit,` a relay circuit, contacts in said circuit, and'snseQfxjdrelay under the control .of the eelledhsteton serving by tsyoperation to einen su'eh contacts and disconnect said signaling circuit. Y A

.17. In an interemmunicating telephone system, a plurality of stations and conductors interconnecting them, one of such stetiens constituting an attendents sta-tion, a mein exchange trunk line ext/ending to such stations, keys at the attendants lstation for calling u desired one of the interconnected stations, a first relay adapted to be energized by the operation of one of such keys, a locking circuit for such relay, a second relay adapted to be energized by the establishment at the called stat-ion of e talking circuit with the trunk line, and a signaling cire-nit closed by the energizetion of the first 1'eley, sucl1 second relay serving by its energization to open such locking circuit.

In testimony whereof I aiiix my signature in presence of two Witnesses.

A. D. T. LIBBY.

Witnesses:

F. O. Reney, C. A. -Smvnneoon 

